The present invention relates to methods for protecting substrates from fire and excessive heat.
The protection of heat sensitive substrates from fire and excessive heat has been an ongoing challenge. The technology which is utilized in preparing compositions for the protection of steel and concrete structural building materials such as columns, beams, girders, and other steel assemblies has been deficient in some measure for the protection of heat sensitive substrates.
Heat sensitive substrates such as plastic coated electrical cables typically have been protected by rubber based wraps or ceramic blankets. A variety of difficulties are associated with these methods. For example, in some instances the "wrap" or "blanket" is an exceptional insulator; so much so that it retains the heat generated by the electrical resistance of the cables and creates an inordinate heat build-up during normal useage. Moreover, the actual application of the "wrap" or "blanket" often is difficult because the physical location of the cables hampers access to the cables and the ability to thoroughly protect them.
Intumescent coating compositions which recently have grown in popularity and have been formulated in a variety of ways to increase the quality of protection for ferrous type substrates quite often do not meet the requirements for the protection of heat sensitive substrates. Compositions for the protection of such substrates must not only be capable of facing the ordinary service life conditions of expansion, contraction and flexing of the substrate due to, for example heating and cooling cycles and exterior climatic conditions such as winds; but also, they must meet additional requirements such as low flame spread and low smoke generation. This is typically because heat sensitive substrates are flammable thus propogate a fire rapidly and generate a great deal of smoke. In addition, depending upon the ultimate end use of the substrate, protective compositions for heat sensitive substrates often must meet stringent test criteria such as the ability to protect the substrate for a specified time period from the rapid rise in temperature experienced during a hydrocarbon fire (i.e., reaching a temperature of 2000.degree. F. (1093.degree. C.) in less than five minutes). Heat sensitive substrates are damaged at a much lower temperature than steel and require a different level of protection.
Heretofore, currently available intumescent compositions have fallen short of the specific requirements for the protection of heat sensitive substrates. Therefore, there is a need for a way in which to protect heat sensitive substrates from fire and excessive heat.